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<div>Crispin and all:</div><div><br></div><div>For method 3, y also think that the same objective can achieved with a downdraft stove.</div><div><br></div><div>This is an example of a japanese downdraft camping stove. It have a wire grate or basket to contain the pellets.</div>
<div><br></div><div><a href="https://www.youtube.com/watch?v=GV0WDudP538">https://www.youtube.com/watch?v=GV0WDudP538</a><br></div><div><br></div><div>I think that this stove operates like a rocket stove. The stove produce a very strong and orange flame because it have to much primary air. The stove produce a lot of smoke at ignition.</div>
<div><br></div><div>This "downdraft rocket stove", with a few modifications, can operate like a method 3 "TLUD" stove. The challenge is to ignite the stove and achieve the secondary flame without smoke. I think this is possible.</div>
<div><br></div><div>Crispin, ¿how is the ignition of the BLDD 6 stove?</div><div><br></div><div><br></div><div>Cheers</div><div>Roberto Poehlmann</div><div>Valdivia, Chile</div><div><br></div><div><br></div><div>"</div>
<div><span style="font-family:arial,sans-serif;font-size:13px">Dear Kirk</span><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">This is the sort of detailed analysis that really helps the whole field of</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">advanced stoves. I really appreciate your taking the time to put it into</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">writing.</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Method three, turned upside down, is a downdraft stove with preheated</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">secondary air and it is a very good way to burn biomass, especially pellets</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">which are predictable. There is no need to elevate the fuel because gravity</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">handles that. I can recommend that anyone trying it use a wire grate, not</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">bars. This is a development of the BLDD stoves from the SeTAR Centre where</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">considerable success has been achieved in reducing PM emissions burning</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">semi-bituminous coals and again in Mongolia burning wet lignite, both with</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">extremely low emissions.</span><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Method 2 - using flamelets to maintain the main fire is a useful idea that</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">can be added to many stoves to overcome some debilitating shortfalls (ie</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">make them practical devices).</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Can I assume, based on your report, that you do not own a combustion</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">analyser?  You have long ago reached the stage where you need one to be able</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">to make better prototypes and to be able to make more generalised</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">statements. Some of the things said in the document are only correct in</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">certain cases. In nearly all stove layouts, if there is air entering from</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">below and exiting the top, the excess air level is too high to get really</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">good results save in narrow circumstances (low variability). If you want to</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">have high turndown, you have to control the EA in order to have a flame</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">remain viable.</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">In the case of the flamelets, part of the reason for your success is that</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">the flamelets are compensating for too much excess air in a turned down</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">condition. If the EA was lower, the flamelets would perhaps be 'less</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">necessary'.</span><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">You described having up to three controllable air sources. What I have been</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">suggesting is that the control of the secondary air can be made automatic if</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">the bottom-in-top-out architecture is abandoned in favour of downdrafted</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">preheating. You are correct, you need three controls, but if the structure</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">is correct, that happens automatically because the heat inside controls the</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">amount of air entering. With a bottom-to-top air path, there is nearly no</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">hope of getting that to happen automatically.</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">With the downdraft layout, there is a lot to be gained in terms of automatic</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">control because all air is downdrafted to the fire chamber. A combination</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">would be downdrafting secondary air, possible the pilot flame air as well,</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">in the amounts needed to cover the range of power envisaged. The draft</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">calculator available on the Stoves website can assist with this while only</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">having a thermocouple to measure gas temps with. You divide the stove into</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">sections and enter the temps are the top and bottom of each and it will</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">calculate the total draft. You can either check the draft of something that</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">works well, or predict what temps or heights you need in order to generate</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">the draft necessary to run the stove at that power.</span><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">I really encourage you to get or borrow a combustion analyser and read the</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">article in Boiling Point on how to use and calculate the necessary numbers</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">that provide guidance.</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Regards</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Crispin</span><br style="font-family:arial,sans-serif;font-size:13px"></div><div><span style="font-family:arial,sans-serif;font-size:13px">"</span></div>
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